Ignition system for caseless rounds in open breech type guns



April 25, 1961 T. STEVENSON 2,981,151 IGNITION SYSTEM FOR CASELESS ROUNDS IN OPEN BREECH TYPE GUNS Filed Nov. 1a, 1958 l8 PERCUSSION TYPE FIRING MEANS INVEN TOR. THOMAS STEVENSON 1; WM-QQWMWWM ATTORNEYS:

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IGNITION SYSTEM FOR CASELESS ROUNDS 1N OPEN BREECH TYPE GUNS r Thomas Stevenson, 1039 Arthur Ave l Huntingdon Valley, Pa. Filed Nov. 18, 1958, sr. N; 714,796 3 '5 Claims. or. s9-1.1) I 1 (Granted under Title as, on. Code 1952 see; 266) The invention described herein may be manufactured and used by or for the Government for govermental pur poses without thepayment to me of any.royalty thereon.

This invention relates to the firing of caseless rounds in open breech type guns and has for an objec txto provide a new and simple percussion system for. firing such a weapon to eliminate the need for the presently used electrical or other connections entering the breech opening. Another object has been to provide a greater approach to uniformity in firing such rounds under widely different ambient temperatures. Yet a further object is to enable a hotter igniter flame to be available for such.

in all kinds of weather and require a quick. disconnection on firing. Yet no satisfactory solution has appeared.

According to this invention such connections have been eliminated with elimination of their attendant ob -f jections. A serious objection to the use of open breech guns with caseless ammunition has been the serious effect Wide temperature variations are found to have in the burning of such ammunition with corresponding varia It is not feasible tions in pressure and effective range. to transport many or even a few different types of caseless rounds, one for a particular temperature range and; anotherfor a different range of ambinet temperatures;

Although it is known that different kinds of igniting flames produce different effects in the same kind of pro pelling charge and differences in the range, 0. one has heretofore realized the desirability of using selected igniting flames, especially in open breech guns with caseless ammunition to compensate for temperature changes and obtain a closer approach to uniformity in range under wide temperature variations. 1 i t Accordingly the present invention providesigniting flames of different temperaturesv and lengths to effect a closer approach to ballistic uniformity with more nearly constancy in range with open breech guns using caseless ammunition under different temperature conditions of the air. By caseless ammunition is usually meant a unit composed of a projectile and propelling charge in which an enclosing casing for propellant is either absent or easily combustible. More specifically under this invention blank cartridges can be selected for the field tem-, perature conditions and fired by percussion after being positioned so that the flame enters a small hole in a side wall of the open breech gun to fire the propellant. The thin side wall of such a gun enables the igniter flame to pass through a small hole without an objectionable amount of heat of the flame being absorbed by the walls Patented Apr. 25, 1961 "ice - connecting stabilizing fins and' projectile and surrounded 'by propellant, there has been a limit to the temperature generated by an igniter flame when such boom is'of aluminum; This isybecause high igniter temperatures would melt; destroy, or damage this boom. Under the present invention when an igniter flame does not have to pass through such boom there is less danger of that boom being raised to its kindling temperature with the igniter flame moving radially inwardly rather than out-' wardly. This invention is distinguished from the old muzzle loading weapon fired by a line of burning powder side the gun: but inside by the powder burning along a line extending through the wall of the gun. The origin Q of the burning powder line started outside but proabsorbed by the thick walls of the gun.

gressed inside as the line of black powder or fuse burned; Were an igniting flame to have been initiated only on the outside of the gun rather than to have a progressive origin, an excessive amount of heat would have been With recoilless and open breech guns the side walls are much thinner for a gun of the same size, enabling them to be lighter in weight. The old' muzzle loaded guns used separate loading ammunition and not caseless rounds as the term is defined herein. a V a The single figure of the drawing shows one embodiment of this invention in an open breech type gun containing a stabilized projectile. 7

Such a gun 10 has a projectile. 11 therein provided with stabilizing fins 12 connected with the main body of the projectile by a boom 13 enclosed in a propelling charge 14 surrounded by a thin easily perforable plastic or preferably easily combustible container 15. With this method of ignition the boom need not be perforated nor contain black powder or other igniting material. Yieldable flaps 16 control recoil and are capable of retaining a projectile in the gun when elevated, to prevent the round from falling out of the gun by gravity.

Beneath the gun is shown some suitable ,form of maga- "zine containing a number of blank cartridges 17 fed to the firing chamber 21 by a' usual follower spring not shown. This magazine is supported at its left end by a threaded sleeve 18engaging corresponding threads in the gun and this sleeve is provided with a generally axial hole 20, through which an igniting flame from the blank cartridge 17 is fired to ignite the propelling charge 14.

which the igniting flame can readily penetrate and ignite the propeller charge 14. This invention was tried out in a millimeter gun having a wall thicknessof .157 inch. The hole for the initiator flame was of an inch in diameter. 7

An outstanding advantage of this invention is increased efiiciency of ignition applied to a gun of the open breech type. Where loaded with a fin stabilized projectile since less than half as much initiator material is needed under this invention as is needed when black powder fills a perforate boom as is customary under the prior practice. Under this invention a weapon system including a gun having a chamber for a propellant 14 is fired by a smaller or auxiliary Weapon system including a 'maga initiator flame passageway or tube is about 2.3879 times 'combination therewith of the improvement in said firing means whereby a more rapid'rate of fire may be attained by elimination of the time consuming tedium of extending and fastening electrical connections in allkinds of weather through the open breech and then electrically firing a propellant in the gun,,said improvement including a straight laterally, directed threaded passageway for an igniter flame leading through a sidewall of said gun into said propellant chamber, means' for positioning a blank cartridge alined with said passageway and adjacent said gun, a trigger operatedpercussion typefiring means for firing a blank cartridge when alined withsaid pas:

the gun wall thickness of .l57'inch. This inside diameter of .375 inch is about .1057 times the bore diameter of the 90 millimeter gun. The term solid propellant does not mean that the caseless propellant 14 has to be in one block because usually a solid propellant is inparticles which may be of various shapes and sizes.

I claim:

1. In an open breech type of recoilless gun having a chamber for reception of a caseless solid propellant in a rear portion of said gun, a second chamber for reception of a main body portion of a projectile in front of the first mentioned chamber, means for holding a round in said gun to prevent it from falling out by gravity when a muzzle of the gun has been elevated; and means for firing a caseless solid propellant in the first mentioned chamber of said gun, the combination therewith of the improvement in said firing means whereby the time consuming tedium of making electrical connections in all kinds of weather and firing a propellant through current supplied by said connections extending through an open breech may be eliminated, said firing means improvement including a substantially straight enclosed flame passageway directed laterally through a side wall of said gun and into said chamber for caseless propellant, means for positioning a blank cartridge in alinement with said passageway, a trigger operated'percussion type firing mechanism for a cartridge positioned at said passageway, and a plurality of blank cartridges some of which are distinctively different by having different types of explosives in cartridge cases of the same diameter maybe selectively presented to said passageway fordirecting initiator flames of difierent available temperatures to compensate for wide ranges of ambient temperature and whereby a faster rate of firing said recoilless gun is obtainable than is possible with the use of electrical connections entering through the open breech type of such guns.

2. A combination according to claim 1 in which blank cartridges are slidable as a unit in a magazine for positioning them one at a time in alinement with said enclosed passageway at an outer end thereof.

3. In an open breech type recoilless gun having a chamber for a caseless propellant in a rear portion of said gun, a projectile chamber in front of said propellant chamber, means for holding a round in said gun to prevent it from falling out of the gun by gravity when a muzzle of the gun has been elevated, said means comprising yieldable flaps the shape of which controls recoil, and means for firing propellant in said chamber, the

sageway, said passageway. having an inside diameter larger than a side wall thickness for the gun.

4. A combination according to claim 3 in which said yieldable flaps engage stabilizing fins on a unitary caseless round when inserted in said gun and said round having propellant located around a boom extending be-,

tween such fins and a main body portion of a projectile whereby a saving of about 50% in initiator explosive for firing a propellant is available in afblank cartridge as compared with what had been, used in said, boomwith the aforementioned electric igniter connectionfentering the open breech for firing an igniter in said .boom..

' 5. In an open breech type recoilless gun .having a chamber for a caseless solid propellant, a projectile chamber at least partially infront of said propellant chamber, means for holding a round in said gun to prevent it from falling out by gravity when a muzzle of the gun is elevated, and means, forfiring said propellant. in the gun, the combination therewith of the improvement in said firing means whereby the rate of .fire .may be increased and the time consuming tedium of making electrical connections in all kindsof weatherlforfiring propellant by current suppliedthrough such connections may be eliminated, said improvement being insaid firing means and including a straight flame passageway from adjacent the mouth of a cartridgecase and with said passageway being directed laterally through a side wall of said gun into said propellant chamber, an inside diameter of said passageway being larger than the wall thickness of said gun, means for positioning a cartridge case containing an explosive with the mouth of such a case at the outer end of said passageway and outside said recoilless gun ,for' directing a flame initially at. least in a direction away from a cartridge, case so positioned and through said passageway when fired for firing a caseless propelling charge in said gun, and a trigger operated percussion type firing means for acartridge so positioned.

References Cited in the file ofthis patent UNITED STATES PATENTS 

